import {
  BufferGeometry,
  FileLoader,
  Float32BufferAttribute,
  Group,
  LineBasicMaterial,
  LineSegments,
  Loader,
  Material,
  Mesh,
  MeshPhongMaterial,
  Points,
  PointsMaterial,
  Vector3
} from '../../three.module.js';

// o object_name | g group_name
const _object_pattern = /^[og]\s*(.+)?/;
// mtllib file_reference
const _material_library_pattern = /^mtllib /;
// usemtl material_name
const _material_use_pattern = /^usemtl /;
// usemap map_name
const _map_use_pattern = /^usemap /;

const _vA = new Vector3();
const _vB = new Vector3();
const _vC = new Vector3();

const _ab = new Vector3();
const _cb = new Vector3();

function ParserState() {

  const state = {
    objects: [],
    object: {},

    vertices: [],
    normals: [],
    colors: [],
    uvs: [],

    materials: {},
    materialLibraries: [],

    startObject: function (name, fromDeclaration) {

      // If the current object (initial from reset) is not from a g/o declaration in the parsed
      // file. We need to use it for the first parsed g/o to keep things in sync.
      if (this.object && this.object.fromDeclaration === false) {

        this.object.name = name;
        this.object.fromDeclaration = (fromDeclaration !== false);
        return;

      }

      const previousMaterial = (this.object && typeof this.object.currentMaterial === 'function' ? this.object.currentMaterial() : undefined);

      if (this.object && typeof this.object._finalize === 'function') {

        this.object._finalize(true);

      }

      this.object = {
        name: name || '',
        fromDeclaration: (fromDeclaration !== false),

        geometry: {
          vertices: [],
          normals: [],
          colors: [],
          uvs: [],
          hasUVIndices: false
        },
        materials: [],
        smooth: true,

        startMaterial: function (name, libraries) {

          const previous = this._finalize(false);

          // New usemtl declaration overwrites an inherited material, except if faces were declared
          // after the material, then it must be preserved for proper MultiMaterial continuation.
          if (previous && (previous.inherited || previous.groupCount <= 0)) {

            this.materials.splice(previous.index, 1);

          }

          const material = {
            index: this.materials.length,
            name: name || '',
            mtllib: (Array.isArray(libraries) && libraries.length > 0 ? libraries[libraries.length - 1] : ''),
            smooth: (previous !== undefined ? previous.smooth : this.smooth),
            groupStart: (previous !== undefined ? previous.groupEnd : 0),
            groupEnd: -1,
            groupCount: -1,
            inherited: false,

            clone: function (index) {

              const cloned = {
                index: (typeof index === 'number' ? index : this.index),
                name: this.name,
                mtllib: this.mtllib,
                smooth: this.smooth,
                groupStart: 0,
                groupEnd: -1,
                groupCount: -1,
                inherited: false
              };
              cloned.clone = this.clone.bind(cloned);
              return cloned;

            }
          };

          this.materials.push(material);

          return material;

        },

        currentMaterial: function () {

          if (this.materials.length > 0) {

            return this.materials[this.materials.length - 1];

          }

          return undefined;

        },

        _finalize: function (end) {

          const lastMultiMaterial = this.currentMaterial();
          if (lastMultiMaterial && lastMultiMaterial.groupEnd === -1) {

            lastMultiMaterial.groupEnd = this.geometry.vertices.length / 3;
            lastMultiMaterial.groupCount = lastMultiMaterial.groupEnd - lastMultiMaterial.groupStart;
            lastMultiMaterial.inherited = false;

          }

          // Ignore objects tail materials if no face declarations followed them before a new o/g started.
          if (end && this.materials.length > 1) {

            for (let mi = this.materials.length - 1; mi >= 0; mi--) {

              if (this.materials[mi].groupCount <= 0) {

                this.materials.splice(mi, 1);

              }

            }

          }

          // Guarantee at least one empty material, this makes the creation later more straight forward.
          if (end && this.materials.length === 0) {

            this.materials.push({
              name: '',
              smooth: this.smooth
            });

          }

          return lastMultiMaterial;

        }
      };

      // Inherit previous objects material.
      // Spec tells us that a declared material must be set to all objects until a new material is declared.
      // If a usemtl declaration is encountered while this new object is being parsed, it will
      // overwrite the inherited material. Exception being that there was already face declarations
      // to the inherited material, then it will be preserved for proper MultiMaterial continuation.

      if (previousMaterial && previousMaterial.name && typeof previousMaterial.clone === 'function') {

        const declared = previousMaterial.clone(0);
        declared.inherited = true;
        this.object.materials.push(declared);

      }

      this.objects.push(this.object);

    },

    finalize: function () {

      if (this.object && typeof this.object._finalize === 'function') {

        this.object._finalize(true);

      }

    },

    parseVertexIndex: function (value, len) {

      const index = parseInt(value, 10);
      return (index >= 0 ? index - 1 : index + len / 3) * 3;

    },

    parseNormalIndex: function (value, len) {

      const index = parseInt(value, 10);
      return (index >= 0 ? index - 1 : index + len / 3) * 3;

    },

    parseUVIndex: function (value, len) {

      const index = parseInt(value, 10);
      return (index >= 0 ? index - 1 : index + len / 2) * 2;

    },

    addVertex: function (a, b, c) {

      const src = this.vertices;
      const dst = this.object.geometry.vertices;

      dst.push(src[a + 0], src[a + 1], src[a + 2]);
      dst.push(src[b + 0], src[b + 1], src[b + 2]);
      dst.push(src[c + 0], src[c + 1], src[c + 2]);

    },

    addVertexPoint: function (a) {

      const src = this.vertices;
      const dst = this.object.geometry.vertices;

      dst.push(src[a + 0], src[a + 1], src[a + 2]);

    },

    addVertexLine: function (a) {

      const src = this.vertices;
      const dst = this.object.geometry.vertices;

      dst.push(src[a + 0], src[a + 1], src[a + 2]);

    },

    addNormal: function (a, b, c) {

      const src = this.normals;
      const dst = this.object.geometry.normals;

      dst.push(src[a + 0], src[a + 1], src[a + 2]);
      dst.push(src[b + 0], src[b + 1], src[b + 2]);
      dst.push(src[c + 0], src[c + 1], src[c + 2]);

    },

    addFaceNormal: function (a, b, c) {

      const src = this.vertices;
      const dst = this.object.geometry.normals;

      _vA.fromArray(src, a);
      _vB.fromArray(src, b);
      _vC.fromArray(src, c);

      _cb.subVectors(_vC, _vB);
      _ab.subVectors(_vA, _vB);
      _cb.cross(_ab);

      _cb.normalize();

      dst.push(_cb.x, _cb.y, _cb.z);
      dst.push(_cb.x, _cb.y, _cb.z);
      dst.push(_cb.x, _cb.y, _cb.z);

    },

    addColor: function (a, b, c) {

      const src = this.colors;
      const dst = this.object.geometry.colors;

      if (src[a] !== undefined) dst.push(src[a + 0], src[a + 1], src[a + 2]);
      if (src[b] !== undefined) dst.push(src[b + 0], src[b + 1], src[b + 2]);
      if (src[c] !== undefined) dst.push(src[c + 0], src[c + 1], src[c + 2]);

    },

    addUV: function (a, b, c) {

      const src = this.uvs;
      const dst = this.object.geometry.uvs;

      dst.push(src[a + 0], src[a + 1]);
      dst.push(src[b + 0], src[b + 1]);
      dst.push(src[c + 0], src[c + 1]);

    },

    addDefaultUV: function () {

      const dst = this.object.geometry.uvs;

      dst.push(0, 0);
      dst.push(0, 0);
      dst.push(0, 0);

    },

    addUVLine: function (a) {

      const src = this.uvs;
      const dst = this.object.geometry.uvs;

      dst.push(src[a + 0], src[a + 1]);

    },

    addFace: function (a, b, c, ua, ub, uc, na, nb, nc) {

      const vLen = this.vertices.length;

      let ia = this.parseVertexIndex(a, vLen);
      let ib = this.parseVertexIndex(b, vLen);
      let ic = this.parseVertexIndex(c, vLen);

      this.addVertex(ia, ib, ic);
      this.addColor(ia, ib, ic);

      // normals

      if (na !== undefined && na !== '') {

        const nLen = this.normals.length;

        ia = this.parseNormalIndex(na, nLen);
        ib = this.parseNormalIndex(nb, nLen);
        ic = this.parseNormalIndex(nc, nLen);

        this.addNormal(ia, ib, ic);

      } else {

        this.addFaceNormal(ia, ib, ic);

      }

      // uvs

      if (ua !== undefined && ua !== '') {

        const uvLen = this.uvs.length;

        ia = this.parseUVIndex(ua, uvLen);
        ib = this.parseUVIndex(ub, uvLen);
        ic = this.parseUVIndex(uc, uvLen);

        this.addUV(ia, ib, ic);

        this.object.geometry.hasUVIndices = true;

      } else {

        // add placeholder values (for inconsistent face definitions)

        this.addDefaultUV();

      }

    },

    addPointGeometry: function (vertices) {

      this.object.geometry.type = 'Points';

      const vLen = this.vertices.length;

      for (let vi = 0, l = vertices.length; vi < l; vi++) {

        const index = this.parseVertexIndex(vertices[vi], vLen);

        this.addVertexPoint(index);
        this.addColor(index);

      }

    },

    addLineGeometry: function (vertices, uvs) {

      this.object.geometry.type = 'Line';

      const vLen = this.vertices.length;
      const uvLen = this.uvs.length;

      for (let vi = 0, l = vertices.length; vi < l; vi++) {

        this.addVertexLine(this.parseVertexIndex(vertices[vi], vLen));

      }

      for (let uvi = 0, l = uvs.length; uvi < l; uvi++) {

        this.addUVLine(this.parseUVIndex(uvs[uvi], uvLen));

      }

    }

  };

  state.startObject('', false);

  return state;

}

//

class OBJLoader extends Loader {

  constructor(manager) {

    super(manager);

    this.materials = null;

  }

  load(url, onLoad, onProgress, onError) {

    const scope = this;

    const loader = new FileLoader(this.manager);
    loader.setPath(this.path);
    loader.setRequestHeader(this.requestHeader);
    loader.setWithCredentials(this.withCredentials);
    loader.load(url, function (text) {

      try {

        onLoad(scope.parse(text));

      } catch (e) {

        if (onError) {

          onError(e);

        } else {

          console.error(e);

        }

        scope.manager.itemError(url);

      }

    }, onProgress, onError);

  }

  setMaterials(materials) {

    this.materials = materials;

    return this;

  }

  parse(text) {

    const state = new ParserState();

    if (text.indexOf('\r\n') !== -1) {

      // This is faster than String.split with regex that splits on both
      text = text.replace(/\r\n/g, '\n');

    }

    if (text.indexOf('\\\n') !== -1) {

      // join lines separated by a line continuation character (\)
      text = text.replace(/\\\n/g, '');

    }

    const lines = text.split('\n');
    let line = '', lineFirstChar = '';
    let lineLength = 0;
    let result = [];

    // Faster to just trim left side of the line. Use if available.
    const trimLeft = (typeof ''.trimLeft === 'function');

    for (let i = 0, l = lines.length; i < l; i++) {

      line = lines[i];

      line = trimLeft ? line.trimLeft() : line.trim();

      lineLength = line.length;

      if (lineLength === 0) continue;

      lineFirstChar = line.charAt(0);

      // @todo invoke passed in handler if any
      if (lineFirstChar === '#') continue;

      if (lineFirstChar === 'v') {

        const data = line.split(/\s+/);

        switch (data[0]) {

          case 'v':
            state.vertices.push(
              parseFloat(data[1]),
              parseFloat(data[2]),
              parseFloat(data[3])
            );
            if (data.length >= 7) {

              state.colors.push(
                parseFloat(data[4]),
                parseFloat(data[5]),
                parseFloat(data[6])
              );

            } else {

              // if no colors are defined, add placeholders so color and vertex indices match

              state.colors.push(undefined, undefined, undefined);

            }

            break;
          case 'vn':
            state.normals.push(
              parseFloat(data[1]),
              parseFloat(data[2]),
              parseFloat(data[3])
            );
            break;
          case 'vt':
            state.uvs.push(
              parseFloat(data[1]),
              parseFloat(data[2])
            );
            break;

        }

      } else if (lineFirstChar === 'f') {

        const lineData = line.substr(1).trim();
        const vertexData = lineData.split(/\s+/);
        const faceVertices = [];

        // Parse the face vertex data into an easy to work with format

        for (let j = 0, jl = vertexData.length; j < jl; j++) {

          const vertex = vertexData[j];

          if (vertex.length > 0) {

            const vertexParts = vertex.split('/');
            faceVertices.push(vertexParts);

          }

        }

        // Draw an edge between the first vertex and all subsequent vertices to form an n-gon

        const v1 = faceVertices[0];

        for (let j = 1, jl = faceVertices.length - 1; j < jl; j++) {

          const v2 = faceVertices[j];
          const v3 = faceVertices[j + 1];

          state.addFace(
            v1[0], v2[0], v3[0],
            v1[1], v2[1], v3[1],
            v1[2], v2[2], v3[2]
          );

        }

      } else if (lineFirstChar === 'l') {

        const lineParts = line.substring(1).trim().split(' ');
        let lineVertices = [];
        const lineUVs = [];

        if (line.indexOf('/') === -1) {

          lineVertices = lineParts;

        } else {

          for (let li = 0, llen = lineParts.length; li < llen; li++) {

            const parts = lineParts[li].split('/');

            if (parts[0] !== '') lineVertices.push(parts[0]);
            if (parts[1] !== '') lineUVs.push(parts[1]);

          }

        }

        state.addLineGeometry(lineVertices, lineUVs);

      } else if (lineFirstChar === 'p') {

        const lineData = line.substr(1).trim();
        const pointData = lineData.split(' ');

        state.addPointGeometry(pointData);

      } else if ((result = _object_pattern.exec(line)) !== null) {

        // o object_name
        // or
        // g group_name

        // WORKAROUND: https://bugs.chromium.org/p/v8/issues/detail?id=2869
        // let name = result[ 0 ].substr( 1 ).trim();
        const name = (' ' + result[0].substr(1).trim()).substr(1);

        state.startObject(name);

      } else if (_material_use_pattern.test(line)) {

        // material

        state.object.startMaterial(line.substring(7).trim(), state.materialLibraries);

      } else if (_material_library_pattern.test(line)) {

        // mtl file

        state.materialLibraries.push(line.substring(7).trim());

      } else if (_map_use_pattern.test(line)) {

        // the line is parsed but ignored since the loader assumes textures are defined MTL files
        // (according to https://www.okino.com/conv/imp_wave.htm, 'usemap' is the old-style Wavefront texture reference method)

        console.warn('THREE.OBJLoader: Rendering identifier "usemap" not supported. Textures must be defined in MTL files.');

      } else if (lineFirstChar === 's') {

        result = line.split(' ');

        // smooth shading

        // @todo Handle files that have varying smooth values for a set of faces inside one geometry,
        // but does not define a usemtl for each face set.
        // This should be detected and a dummy material created (later MultiMaterial and geometry groups).
        // This requires some care to not create extra material on each smooth value for "normal" obj files.
        // where explicit usemtl defines geometry groups.
        // Example asset: examples/models/obj/cerberus/Cerberus.obj

        /*
           * http://paulbourke.net/dataformats/obj/
           *
           * From chapter "Grouping" Syntax explanation "s group_number":
           * "group_number is the smoothing group number. To turn off smoothing groups, use a value of 0 or off.
           * Polygonal elements use group numbers to put elements in different smoothing groups. For free-form
           * surfaces, smoothing groups are either turned on or off; there is no difference between values greater
           * than 0."
           */
        if (result.length > 1) {

          const value = result[1].trim().toLowerCase();
          state.object.smooth = (value !== '0' && value !== 'off');

        } else {

          // ZBrush can produce "s" lines #11707
          state.object.smooth = true;

        }

        const material = state.object.currentMaterial();
        if (material) material.smooth = state.object.smooth;

      } else {

        // Handle null terminated files without exception
        if (line === '\0') continue;

        console.warn('THREE.OBJLoader: Unexpected line: "' + line + '"');

      }

    }

    state.finalize();

    const container = new Group();
    container.materialLibraries = [].concat(state.materialLibraries);

    const hasPrimitives = !(state.objects.length === 1 && state.objects[0].geometry.vertices.length === 0);

    if (hasPrimitives === true) {

      for (let i = 0, l = state.objects.length; i < l; i++) {

        const object = state.objects[i];
        const geometry = object.geometry;
        const materials = object.materials;
        const isLine = (geometry.type === 'Line');
        const isPoints = (geometry.type === 'Points');
        let hasVertexColors = false;

        // Skip o/g line declarations that did not follow with any faces
        if (geometry.vertices.length === 0) continue;

        const buffergeometry = new BufferGeometry();

        buffergeometry.setAttribute('position', new Float32BufferAttribute(geometry.vertices, 3));

        if (geometry.normals.length > 0) {

          buffergeometry.setAttribute('normal', new Float32BufferAttribute(geometry.normals, 3));

        }

        if (geometry.colors.length > 0) {

          hasVertexColors = true;
          buffergeometry.setAttribute('color', new Float32BufferAttribute(geometry.colors, 3));

        }

        if (geometry.hasUVIndices === true) {

          buffergeometry.setAttribute('uv', new Float32BufferAttribute(geometry.uvs, 2));

        }

        // Create materials

        const createdMaterials = [];

        for (let mi = 0, miLen = materials.length; mi < miLen; mi++) {

          const sourceMaterial = materials[mi];
          const materialHash = sourceMaterial.name + '_' + sourceMaterial.smooth + '_' + hasVertexColors;
          let material = state.materials[materialHash];

          if (this.materials !== null) {

            material = this.materials.create(sourceMaterial.name);

            // mtl etc. loaders probably can't create line materials correctly, copy properties to a line material.
            if (isLine && material && !(material instanceof LineBasicMaterial)) {

              const materialLine = new LineBasicMaterial();
              Material.prototype.copy.call(materialLine, material);
              materialLine.color.copy(material.color);
              material = materialLine;

            } else if (isPoints && material && !(material instanceof PointsMaterial)) {

              const materialPoints = new PointsMaterial({size: 10, sizeAttenuation: false});
              Material.prototype.copy.call(materialPoints, material);
              materialPoints.color.copy(material.color);
              materialPoints.map = material.map;
              material = materialPoints;

            }

          }

          if (material === undefined) {

            if (isLine) {

              material = new LineBasicMaterial();

            } else if (isPoints) {

              material = new PointsMaterial({size: 1, sizeAttenuation: false});

            } else {

              material = new MeshPhongMaterial();

            }

            material.name = sourceMaterial.name;
            material.flatShading = sourceMaterial.smooth ? false : true;
            material.vertexColors = hasVertexColors;

            state.materials[materialHash] = material;

          }

          createdMaterials.push(material);

        }

        // Create mesh

        let mesh;

        if (createdMaterials.length > 1) {

          for (let mi = 0, miLen = materials.length; mi < miLen; mi++) {

            const sourceMaterial = materials[mi];
            buffergeometry.addGroup(sourceMaterial.groupStart, sourceMaterial.groupCount, mi);

          }

          if (isLine) {

            mesh = new LineSegments(buffergeometry, createdMaterials);

          } else if (isPoints) {

            mesh = new Points(buffergeometry, createdMaterials);

          } else {

            mesh = new Mesh(buffergeometry, createdMaterials);

          }

        } else {

          if (isLine) {

            mesh = new LineSegments(buffergeometry, createdMaterials[0]);

          } else if (isPoints) {

            mesh = new Points(buffergeometry, createdMaterials[0]);

          } else {

            mesh = new Mesh(buffergeometry, createdMaterials[0]);

          }

        }

        mesh.name = object.name;

        container.add(mesh);

      }

    } else {

      // if there is only the default parser state object with no geometry data, interpret data as point cloud

      if (state.vertices.length > 0) {

        const material = new PointsMaterial({size: 1, sizeAttenuation: false});

        const buffergeometry = new BufferGeometry();

        buffergeometry.setAttribute('position', new Float32BufferAttribute(state.vertices, 3));

        if (state.colors.length > 0 && state.colors[0] !== undefined) {

          buffergeometry.setAttribute('color', new Float32BufferAttribute(state.colors, 3));
          material.vertexColors = true;

        }

        const points = new Points(buffergeometry, material);
        container.add(points);

      }

    }

    return container;

  }

}

export {OBJLoader};
